1. Field of the Invention
The present invention relates to an electric motor controller for controlling an electric motor that drives an opening/closing member for a vehicle, for example.
2. Background Art
For example, a vehicle is provided with opening/closing members such as door windows, a sun roof, slide doors, etc., and electric motors for driving these opening/closing members, and electric motor controllers for controlling the electric motors. In these electric motor controllers, a controller for controlling an electric motor for opening/closing a window is called as a power window device (or window opening/closing controller). The power window device generally rotates a motor serving as an electric motor forwardly or reversely upon operation of a switch to upwardly or downwardly move the window glass of a door, thereby opening/closing the window.
FIG. 1 is a block diagram showing the electrical construction of the power window device. 1 represents an operation switch for opening/closing a window, 2 represents a motor driving circuit for driving a motor 3, 4 represents a rotary encoder for outputting pulses synchronous with the rotation of the motor 3, 5 represents a pulse detecting circuit for detecting pulses output from the rotary encoder 4, 6 represents a memory constructed by ROM, RAM or the like, and 8 represents a controller constructed by CPU for controlling the opening/closing operation of the window and a memory.
Upon operating the operation switch 1, a window opening/closing instruction is given to the controller 8, and the motor 3 is forwardly or reversely rotated by the motor driving circuit 2. By the rotation of the motor 3, a window opening/closing mechanism interlocked with the motor 3 is actuated to open/close the window. The pulse detecting circuit 5 detects pulses output from the rotary encoder 4, and the controller 8 calculates the open/close amount of the window and the rotational speed of the motor on the basis of the detection result and controls the rotation of the motor 3 through the motor driving circuit 2.
FIG. 2 is a diagram showing the construction of an sample of the operation switch 1. The operation switch 1 comprises an operation knob 11 that is rotatable around the axis Q in the direction of ab, a rod 12 provided integrally with the operation knob 11, and a well-known slide switch 13. 14 represents an actuator of the slide switch 13, and 20 represents a cover of a switch unit in which the operation switch 1 is installed. The lower end of the rod 12 is fitted to the actuator 14 of the slide switch 13. When the operation knob 11 is rotated in the direction of ab, the actuator 14 is moved in a direction of cd through the rod 12, and the contact point (not shown) of the slide switch 13 is switched in accordance with the movement position of the actuator 14.
The operation knob 11 is switchable to each of an auto-close AC position, a manual-close MC position, a neutral N position, a manual-open MO position and an auto-open AO position. FIG. 2 shows a state where the operation knob 11 is located at the neutral position N. When the operation knob 11 is rotated from this position in the direction of a by a fixed amount and set to the manual-close MC position, a manual-close operation under which the window is manually closed is carried out. When the operation knob 11 is further rotated from the above position in the direction of a and set to the auto-close AC position, an auto-close operation under which the window is automatically closed is carried out. Furthermore, when the operation knob 11 is rotated from the neutral N position in the direction of b by a fixed amount and set to the manual-open MO position, a manual-open operation under which the window is manually opened is carried out. When the operation knob 11 is further rotated from the above position in the direction of b and set to the auto-open AO position, an auto-open operation under which the window is automatically opened is carried out. The operation knob 11 is provided with a spring (not shown), and when a hand is released from the rotated operation knob 11, the operation knob 11 is returned to the neutral N position by the force of the spring.
In the case of the manual operation, the window closing or opening operation is carried out during only the time period when the operation knob 11 is continued to be held at the manual-close MC or manual-open MO position by a hand. When the hand is released from the knob 11 and thus the knob is returned to the neutral position N, the window closing or opening operation is stopped. On the other hand, in the case of the automatic operation, once the operation knob 11 is rotated to the auto-close AC or auto-open AO position, the window closing or opening operation is subsequently continuously carried out even when the hand is released from the operation knob 11 and thus the knob is returned to the neutral N position.
FIG. 3 is a diagram showing an example of the window opening/closing mechanism provided to each window of the vehicle. 100 represents a window, 101 represents a window glass that opens/closes the window 100, 102 represents an X arm type window opening/closing mechanism. The window glass 101 is upwardly and downwardly moved by actuation of the window opening/closing mechanism 102. The upward movement of the window glass 101 closes the window 100, and the downward movement of the window glass 101 opens the window 100. In the window opening/closing mechanism 102, 103 represents a support member secured to the lower end of the window glass 101. 104 represents a first arm one end of which is fitted to a support member 103 and the other end of which is rotatably supported by a bracket 106, and 105 represents a second arm one end of which is fitted to the support member 103 and the other end of which is fitted to a guide member 107. The first arm 104 and the second arm 105 are connected to each other at the intermediate portions thereof through a shaft. 3 represents the motor described above, and 4 represents the rotary encoder described above. The rotary encoder 4 is connected to the rotational shaft of the motor 3, and outputs pulses whose number is proportional to the rotation amount of the motor 3. The number of pulses output from the rotary encoder 4 within a predetermined time is counted, whereby the rotational speed of the motor 3 can be detected. Furthermore, the rotation amount of the motor 3 (the movement amount of the window glass 101) can be calculated from the output of the rotary encoder 4.
109 represents a pinion rotated by the motor 3, and 110 represents a fan-shaped gear that is engaged with the pinion 109 and rotated. The gear 110 is fixed to the first arm 104. The motor 3 is rotatable in forward and reverse directions, and rotates the pinion 109 and the gear 110 by the rotation thereof in the forward and reverse directions, so that the first arm 104 is rotated in the forward and reverse directions. Following this rotation, the other end of the second arm 105 is slid in the lateral direction along the groove of the guide member 107, and the support member 103 is moved in the vertical direction to upwardly and downwardly the window glass 101, so that the window 100 is opened and closed.
The power window device as described above has a function of detecting sticking of an object when the auto-close operation is carried out under the state that the operation knob 11 is located at the auto-close AC position of FIG. 2 or when the manual-close operation is carried out under the state that the operation knob 11 is located at the manual-close MC position. That is, as shown in FIG. 4, when an object Z is stuck in a gap of the window glass 101 during the closing operation of the window 100, the sticking is detected to stop the closing operation of the window 100 or switch the closing operation to the opening operation. Particularly, the window 100 is automatically closed during the auto-close operation, and thus when a hand or a neck is erroneously stuck, it is necessary to prohibit the closing operation and prevent a human body from being injured. Therefore, such a sticking detecting function is provided. When sticking is detected, for example, the rotational speed of the motor 3 which corresponds to the output of the pulse detecting circuit 5 is read by the controller 8 as needed, the present rotational speed and the previous rotational speed are compared with each other, and the presence or absence of rotation abnormality of the motor 3 is judged on the basis of the comparison result, thereby judging the presence or absence of the sticking from the judging result. Specifically, when the object Z is stuck in the window 100, there occurs such abnormality that the load of the motor 3 is rapidly increased and the rotational speed is rapidly reduced, and the difference between the present rotational speed and the previous rotational speed is increased. Therefore, when the difference exceeds a threshold value, it is judged that the rotation abnormality of the motor 3 and sticking occur. Furthermore, even when the rotational speed of the motor 3 is pulsated (varies upwardly and downwardly) due to disturbance such as vibration or the like when the vehicle runs on a bad road, in order to make no erroneous judgment as to sticking and also reduce the sticking detection load and thus deaden a pain when stuck, the difference between the present rotational speed and each of plural different past rotational speeds is calculated, and when all the differences exceed a threshold value, occurrence of sticking is judged (see U.S. Pat. No. 3,553,276 (Patent Document 1), for example).
If it is judged that rotation abnormality of the motor 3 occurs when all the differences of the present rotational speed and the plural past rotational speeds exceed the threshold value as in the case of the related art, the erroneous detection of the rotation abnormality due to the effect of disturbance can be reduced. However, when rotation abnormality of the motor 3 due to sticking of the object Z in the window 100 occurs, it takes much time to detect the rotation abnormality concerned because the processing waits until all the differences exceed the threshold value. When the detection of the rotation abnormality of the motor 3 due to sticking is late, the stop of the motor 3 or the control of the reverse rotation is delayed, so that the closing operation of the window 100 is not prohibited and thus the probability that a human body is injured is increased.